Field of the Invention
The present invention relates to electrical plugs and, more specifically, to an electrical plug with built in function for self unplugging in response to a current change.
Description of the Related Art
The introduction of mobile or portable computing and communication devices is rapidly changing our information society. Laptops or smart-phones equipped with wireless technologies allow users to communicate with other users, accomplish their tasks, accessing and sharing information sources anytime and anywhere. It is expected that the total number of mobile device users will continue to grow significantly with this trend especially in developing countries.
Mobile devices such as portable laptop computers, cell phones, tablet devices or the like are rechargeable battery powered devices, which are often equipped with power chargers or transformers. Adapters can convert AC power to DC power which is needed to charge the rechargeable batteries. Power adapters can also be designed as special plugs to plug into a wall power outlet. It is often very inconvenient and tedious activity for a mobile device user to routinely remove such charger plugs from wall outlets, for example, when the mobile device is charged or the user wants to leave that location. In such situations, the users often attempt to pull the cord in order to quickly remove the plug from the socket.
However, such pulling of the plug from a socket often damages electrical cords and plugs rendering them useless in a short usage time. Furthermore, such devices requiring an adapter continue consuming power if they are left plugged in. Even if the batteries are fully charged such devices keep drawing a trickle of standby power, typically, in the range of 200 to 900 milliwatt (mW). Standby power is defined as the power consumed while products are turned off or otherwise performing no useful function. According to a research conducted by Lawrence Berkeley National Laboratory (LBNL), about 10% of a typical residential electric bill is spent on standby power. Most electronic products continue to consume power unless they are unplugged. Particularly, if the devices using chargers are left connected to a power outlet, the adapters continuously get warm even if they are not used by the devices because they continuously draw and use standby power by converting it to heat energy.
Many existing chargers or other devices sold in the consumer market reduce stand-by power electronically but they still have measurable energy consumption, typically a consumption of less 300 mW. This is undesirable from the power consumption standpoint; therefore power management is critical consideration in mobile device design. The LBNL study recommends unplugging small appliances if they are not used for a prolonged period. The continuous power consumption of portable devices after the battery is fully charged also has a very detrimental effect on battery life and the batteries become incapable of holding charge after a few months. As such, considering the above mentioned popularity of rechargeable battery powered devices nowadays, even a partial solution to this unnecessary energy consumption could have major economic benefits.
Thus, it will become readily apparent that it would be highly desirable to provide the mobile devices with a charger auxiliary or enhancement having the capability of separating itself from an electrical outlet when the charging is complete or when the user wants to relocate the charger auxiliary or enhancement.